The programme filmed patients being pinned down and slapped, doused in cold water and repeatedly taunted and teased – despite warnings by whistleblower Terry Bryan, a senior nurse, who had reportedly alerted the home's management and the CQC several times. His concerns were not followed up, it has been claimed.

Nine men and three women have been arrested and bailed by Avon and Somerset Police in connection with the investigation into the abuse.

These included failing to identify risks to patients, not responding to complaints, not making robust investigations into staff conduct and having no arrangements to protect people "against unlawful or excessive use of restraint".

Amanda Sherlock, the CQC's director of operations said: "This report is a damning indictment of the regime at Winterbourne View and its systemic failings to protect the vulnerable people in its care.

"It is now clear that the problems at Winterbourne View were far worse than were initially indicated by the whistleblower. He has stated that he was not aware of the level of abuse until he saw the footage from the secret filming.

"We now know that the provider [Castlebeck] had effectively misled us by not keeping us informed about incidents as required by the law.

"Had we been told about all these things, we could have taken action earlier. We will now consider whether it would be appropriate to take further legal action.

"CQC has already acknowledged that we would have acted earlier if the evidence from the television report had been made available to us. However, it is incorrect that CQC had failed to act on warnings by the whistleblower.

"Our internal investigation has confirmed that while we were aware of those concerns, our inspector believed they were being dealt with through the local safeguarding process involving a number of agencies.

"We should have contacted the whistleblower directly – and this will be one of the issues which will be addressed by the independently-led serious case review."

She added: "Although Winterbourne View is now closed, we will continue to monitor Castlebeck's other services closely.

"The most important outcome of all this is that the people who had been living at Winterbourne View are no longer subject to this culture of abuse.

"Our plans for a programme of random, unannounced inspections of hospitals providing care for people with learning disabilities are well underway and we will report back in due course."

The commission said its review of Winterbourne View began immediately after it was informed by Panorama that it had gathered evidence over several months, including secret filming to show serious abuse of patients.

Inspectors had considered taking urgent action to close the centre, but decided it was in the best interests of the patients to allow NHS and local authority commissioners further time to find alternative placements.

There had been an immediate stop on admissions and extra staff were brought in to protect patients until they could be moved.

"When they were satisfied that those arrangements were in place, CQC took enforcement action to remove the registration of Winterbourne View, the legal process to close a location."

The commission said that over the past four months it had reviewed and inspected all the services provided by Castlebeck at its 19 hospitals and care homes in England. The results would be published at the end of July.

"Where we have identified concerns, measures are in place to address the problems and to ensure the safety of people using services."

Castlebeck's chief executive, Lee Reed, said: "We are truly sorry for the failures which led to the terrible mistreatment suffered by patients at Winterbourne View.

"As soon as the company was made aware of the appalling misconduct of staff, we alerted the police and other relevant authorities. We then took immediate remedial steps to safeguard the welfare of all our service users. This work is ongoing, and is our absolute priority."

Reed said the company was determined that its safeguarding and welfare procedures should be the best in the care industry.

An independent inquiry by PricewaterhouseCoopers (PWC) into Castlebeck's company-wide policies and procedures would report later this month.

Martin Green, its chief executive, said: "The CQC has talked about failures by the provider and by local health and social care services, but has not fully acknowledged that cases like this also show a fundamental flaw in its own performance.

"If the quality assurance system is to be left entirely to providers and local safeguarding authorities, it raises the question as to why are we paying the CQC so much to deliver so little?"